Re: How to use not equal and or

On Fri, Aug 2, 2013 at 2:55 PM, Jesus Avila <[e-mail]> wrote:

> ingresa = gets.chomp
>                ingresa = ingresa.downcase

BTW, a tip: you can combine these two as "ingresa = gets.chomp.downcase".  :-)

>    if ingresa !="sum"||ingresa !="sub"||ingresa !="mul"||ingresa !="div"

Close!

Sounds it out in English.  "If it's not sum, or it's not sub, or it's
not mul, or it's not div".  Or in my probably-bad Spanish (which I'm
guessing might be your first language), "Si no esta sum, o no esta
sub, o no esta mul, o no esta div".  Doesn't that just sound logically
wrong to you, even in human-language?  Now, think about what small
change would make the logic correct, in human-language.  Or, just how
you would say it, in human.  Then make that change in Ruby.

Alternately, you could do something like "if it's sum, add them, else
if it's sub, subtract, else if it's mul, multiply, else if it's div,
divide, else complain".  You could do that with an if-elsif-else
chain, or a case statement, which is a very common way of acting on
one of several options.

Lastly, another general tip: your code would be more legible, and
possibly easier for you to edit, with spaces in it, like so:

    if ingresa != "sum" || ingresa != "sub" || ingresa != "mul" ||
ingresa != "div"

-Dave

-- 
Dave Aronson, the T. Rex of Codosaurus LLC,
secret-cleared freelance software developer
taking contracts in or near NoVa or remote.
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